Machines such as, for example, dozers, motor graders, wheel loaders, and other types of heavy equipment are used to perform a variety of tasks. The completion of some of these tasks requires operation on or near steep inclines that, if inappropriately traversed by a machine, have the potential to roll the machine over, resulting in equipment damage and possible injury to the operator. When under the direct control of a human operator, the likelihood of rollover may be estimated by the operator and appropriate avoidance measures manually implemented. However, in some situations, rollover may be difficult for the operator to anticipate and, without suitable automated safety measures in place, rollover may be unavoidable. This rollover potential may be even greater when the machine is remotely or autonomously controlled.
One automated safety measure intended to prevent rollover is described in U.S. Pat. No. 6,954,140 (the '140 patent) issued to Holler on Oct. 11, 2005. The '140 patent describes a rollover prevention device suitable for an on-highway vehicle having a high center of gravity, where the vehicle has the potential to rollover when cornering at high vehicle speeds. The device has an electronic control unit that receives signals from wheel velocity, engine revolution, and engine load sensors. Based on these signals, the electronic control module calculates lateral acceleration, wheel slip differences, and drive torque. When the calculated values indicate the likelihood of rollover, the electronic control unit alerts the operator to potentially dangerous driving conditions and automatically reduces the velocity of the vehicle through the application of vehicle brakes. By reducing the velocity, the vehicle's likelihood of rollover may also be reduced.
Although the device of the '140 patent may minimize the likelihood of vehicle rollover caused by high speed cornering, it may do little to prevent rollover from occurring as a result of the vehicle traversing steep terrain. That is, because the device of the '140 patent initiates countermeasures based only on wheel and engine conditions, no preventative measures may be implemented when the wheel and engine conditions fall within normal operating ranges, even though the likelihood of rollover from excessive inclines may still be great. And, because the device of the '140 patent only slows the travel speed of the vehicle, which is not a major factor in rollovers caused by traversing excessive inclines, rollover may still be possible, even if properly detected.
The disclosed system is directed to overcoming one or more of the problems set forth above.